How can I avoid getting thrush in the first place?

The following measures are advisable for keeping the vulva and vagina healthy:

Washing once a day or so with water but without soap, since soap disturbs the natural pH balance of the vagina. Other measures are seldom necessary or advisable. Two notable examples: so-called "feminine hygiene sprays" are unnecessary, may be generally harmful, and have been known to cause severe allergic reactions. Vaginal douching is generally not necessary and has been implicated in helping to cause bacterial vaginosis (BV) and candidiasis ("yeast infections").
After using the toilet, wipe from the front toward the back to avoid introducing bacteria from the anal area into the vulva.
Drink plenty of water and urinate frequently and as soon as possible when you feel the need, to help flush bacteria out of the urinary tract and avoid urinary tract infections. For the same reason, try to urinate before and after sex.
Change out of a wet swimsuit or other wet clothes as soon as possible.
Avoid fragrances, colors, and "deodorants" in products that contact the vulva/vagina: sanitary pads, tampons, toilet paper. Some women who are sensitive to these substances should also avoid bubble baths and some fabric detergents and softeners.
Avoid wearing leather trousers, tight jeans, panties made of nylon or other synthetic fabrics, or pantyhose without an all-cotton crotch (not cotton covered by nylon - cut out the nylon panel if necessary).
Anything which has been in contact with the anal area should be thoroughly washed with soap and water or a similar disinfectant before coming in contact with the vulva or vagina.
Use condoms, practice safer sex, know your sex partners, ask sex partners to practice basic hygiene (soap and water) of the genitals. Use artificial lubrication during the intercourse if the amount naturally produced is too small.

Be careful with objects inserted inside the vagina. Improper insertion of objects into any body opening can cause damage: infection, cutting, piercing, trauma, blood loss, etc.

Women who are unable to walk are more likely to have infections. The problem can be prevented according to above-mentioned and following measures:

Wash crotch and rectal areas with neutral soap and large amount of warm running water, every morning and evening. The disabled person can sit on a shower chair with an open seat or on a toilet. Use a shower head or water container to wash more directly.
Use towel and blowdryer to dry.
Apply a little body powder on the skin of the areas to absorb perspiration.
Avoid sitting on plastic or synthetic materials. Wear loose underpants and change twice or three times a day.